Method of and apparatus for electrical signaling



E. H. LOFTIN 1,877,920

METHOD OF AND APPARATUS FOR ELECTRICAL SIGNALING Sept. 20, 1932.

Z SheetS-Sheet 1 INVENTOR Filed Oct. 4, 1924 ,E. H. LQFTIN 1,877,920

METHOD OF AND APPARATUS FOR ELECTRICAL SIGNALING Sept. 20, 1932.

Filed oc't. 4, 1924 2 Sheeis-Sheet 7 i w Katmai wz zw m N N Qzw txm 5.2352 1 1 W INVENTOR Patented Sept. 29, 1932 EDWARD H. LOFTIN, OF

NEW YORK, N. Y., ASSIGNOR '10 GENERAL RAILVAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK PATENT OFFICE METHOD OE AND APPARATUS FOR ELECTRICAL SIGNALING Application filed October 4, 1924. Serial No. 741,702.

lVhile my invention relates generally to systems of electrical signaling, it has for a particular object the proin'sion of a system of railway signaling.

A particular object is to provide a system that is simple and efiective, and yetone that will furnish the locomotive operator with a large amount of information as to track conditions.

Anotherobject is to use the rails or trackways as electrical circuits to carry the signal currents, and to use the same signal currents to cause the operation of the wayside visual signals as well as the visual signals and automatic controls on the locomotive.

A further object is to superimpose upon the track currents definite code or signal combinations indicative of track conditions, to be able to vary the combinations in accordance with changing track conditions, and to selectively interpret the signal combinations on the locomotive into visual or other signals in keeping with the track conditions.

A still further ob]ect 1S to prevent the changing of the signaling currents in accordance with signal combinations from interfering with the wayside signal governing devices where the change does not demand a new setting of the wayside visual signals.

An important object is to provide for cur' rent failures through the systemsi'ndicating a.danger condition in the par of the system affected by the current failure.

The system also provides means for definitely indicating open draw bridges, open switches, workmen engaged in track work not permitting traflic, and the like, as well as means permitting the locomotive leaving signaled territory and reentering signaled territory, and being definitely informed of these facts.

Other objects and advantages will be ob vious to those skilled in the art following a description of the system and discussion of its mode of operation.

In carrying out my invention I employ as a means of communication between the trackway and vehicle a form of Baudot code sig-.

ber of codes or signal combinations, each one plete system;

Fig. 2 diagrammatically illustrates a provision that may be made at the exit end of signaling territory to inform the locomotive of the fact that signaling territory is being.

left, i

- Fig. 3 diagrammatically illustrates a provision that may be made at the entrance end of signaling territory to inform the locomotivcg that signaling territory is being entered, an

Figs. 4; and 4a are diagrams explanatory of the code signal formation.

Referring to Fig. 1 the reference numerals 1, 1 designate the track rails of a railway over which tratlic normally moves in the direction indicated by the arrows; that is, from left to right. The rails are divided, by means of insulating joints 2, into a plurality of successive track sections or blocks A-B, BC, C.D, etc. The track in block (3-1) is shown as broken-but it will be understood windings 3 and 4, and a rotor 5 which actuates the contact finger 6. The winding 3,

which I will term the track windin is connected directly with the track rails of the corresponding block, while the other winding 4, which I will term the polarizing winding, is permanently supplied with alternating current from the same source as the track rails, via the supply mains 7 and generator 7a. With such a relay when current is sent through the track winding 3 in one phase the rotor 5 is actuated in one sense, when current is sent through the winding in an op posed phase the rotor 5 is actuated in the opposite sense, and when there is no current in the track winding, or none in the polarizing winding, or none in both windings, the relay is deenergized and the rotor takes up a neutral position. The relay therefore provides for three positions based on shifting phase of current in the track circuit and stopping current fiow.

The contact linger 6 is arranged to control three circuits through making (position) contact with contactors 8, 9 and 10. Each one of these circuits includes one of the signal lamps G, Y, R, the three lamps comprising the usual wayside visual signaling system in which the lamp G has a green lens to indicate clear, the lamp Y a yellow lens to indicate caution, and the lamp R a red lens to indicate danger. The same currents that operate these lamps may be employed to set other visual signals, such as semaphore arms, if desi ed. The lamp circuits are shown as deri lng their currents from the mains 7, though any other suitable current source may be employed.

The current passing through lamp R energizes relay 11, and current through eithelamp Y or G energizes the relay 12, resulting in control of the lever 13 to throw either of the two signal producing wheels 15 or 16 under the brush 17, the two wheels being rotatably fixed but slidably mounted on the shaft of the motor 18, or the lever may as well move the brush 17 in lieu of the wheels. The position of the lever 13 also determines the phase of the current supplied to the transformer T through operation of the polechanging switch 19. Resistance 20, in circuit with the feeder to transformer T prevents eXcessive current being drawn in case of short circuit of the track circuit as happens when the block is occupied by one or more cars.

The signal producing wheels 15 and 16, being one at a time in circuit with the feeder to the track circuit superimpose upon the track currents interruptions which may be so chosen in time and number as to make definite signal or code combinations in a manner which will be described later. Wheels arranged for definite code combinations distinctive of the particular track conditions at different points may be inserted as desired. For instance, there may be chosen ten code combinations all of which have as a first meaning, track clear, but the first one of which adds, sharp curve, slow down; the second adds, up-grade open throttle; the

third adds, draw bridgeslow speed; and

so on. The code combinations are for use on the locomotive, and the manner of getting them there and making use of them will be described later.

The description so far outlines the general system for exciting the track circuits, and before proceeding with special features and the communication of the signals to the locomotive, the operation of the system so far out-lined will be recited:

Beginning with block CD, if there is a car in the block, a broken rail, or other con ditions such as the closur of short-circuiting switch 2-1 (the purpose of which will be described later), which prevents track current from exciting the winding 3 of relay H at point C, the relay H is deenergized and contact lin er 6 takes up a neutral position making contact with contactor 10. This closes the circuit through lamplt which is indicated as lighted, thus setting the wayside visual signal at C to a danger or stop indication. Current also flows through relay 11 which, acting through lever 13, sets brush 17 on signaling producing wheel 15 and pole changing switch 19 to the right. This setting permits the excitation of track circuit BC with current of one phase having superimposed upon it interruptions of a definite code combination determined bythe structure of wheel 15. The track current passes through winding 3 of relay H at point B, and its phase is such as to actuate the rotor 5 in a clockwise direction to make contact between contact linger 6 and contactor 8. As before stated, there are interruptions in the current due to signal wheel 15 so that the relay H is preferably constructed suficiently slow acting or damped to prevent response or chattering due to these interruptions. I will explain later how the interruptions are made of very short duration and form only a small part of the time of one revolution of the signal producing wheel, thus making the matter of preventin response of the relays H very simple. Current passes through the contactor 8 to lamp Y, indicated as lighted, thus setting the wayside visual signal t B to a caution indication. Likewise, the code combination superimposed by wheel 15 on the current in block BC is one chosen to interpret caution. Current also flows through relay 12 at B, thus setting the lever 13 the reverse of the setting at point- C, which sets brush 17 on signal producing wheel 16 and pole-changing switch 19 to the left. The track circuit of block AB is therefore excited with current opposite in phase to the current in block BC and the current has superimposed upon it code combinations due to wheel 16 which are difierent from wheel 15. As a result rotor 5 of relay H at point A is actuated in an anti-clockwise sense to make contact between contact finger 6 and contactor 9, thus sending current through lamp G, indicated as lighted, setting the Zoo be clear indications, the same setting of the pole-chan in switch 19 and the si nal- L :3 b t: producing wheels and-16 at thepoint A as at the point B will suffice, so that one relay 12 through which currents of both lamps Y andG pass sufices for setting the polechanging switch and wheels. As before stated, the wheels 15 and 16 at thediiferent points may have different code combinations, butin general the combinations on wheel 15 should come under the general head of caution and combinations on wheel 16 under the general head of clear.

The system is particularly adapted to making special signals to indicate special roadway conditions, one of which I have illustrated'in the block 'G-'D., in which 22 represents a drawbridge. he drawbridge is arranged toclose-circuit the circuit containing battery 25 and-relay 26 when closed for train traffic, and to open circuit the system when opened for water traffic. When the drawbridge is open the normal block track current is interrupted so that without any special provisions, the signals at point C would be set at danger indication, but

the usual interpretation given to a danger indication is to stop and then proceed slowly, leaving it to the engine operator to ascertain the cause of the danger indication. lVith my system a signal can be transmitted to the locomotive engineer beforehe arrives at the drawbridge telling him to stop and stay, which signal will continue as long as the drawbridge is open, as follows:'Current is supplied to the track circuit at theentrance side of the drawbridge through a special transformer ST when opening of the drawbridge causes relay 26 to release the switch 27 to close the connection of transformer ST to the track circuit. Some distance in ad Vance of the drawbridge, as at point X, the trackcircuit is connected to a short circuiting switch 21 which operates in unison with switch 27. A code signal producing wheel 28, on the shaft of the motor '18, superimposes a special code signal combination on the current in the track between the point X and the drawbridge. The switch 21 short circu ts the special signal current from the track winding 3 of the relay H at the point C. A track switch into a siding or spur could be made to operate this special signal connection in the same'way as the drawbridge illustrated, thus giving protection againsta switch opening. v

The operation is as follows: with the drawbridge 22' closed the block track circuit is normal-and the relay is excited by the normal track-currents. When the drawbridge is open the normal track currents are interrupted and a special signal current is impressed on the-track between the point X and the drawbridge. The track circuit betweenthe points 0 and X is withoutcurrent due to short circuit by switch 21. he signals atC are therefore set at danger. locomotive arriving at C notes a normal danger signal and proceeds into'the sec tion CX where the absenceof current causes an application of brakes to stop the locom ti've which stop is not permanent, but permits proceeding at low speed after stopping. Upon proceeding beyond point X the locomotive receives the special signal to stop and stay which remains impressed as long as the drawbridgeis open.

b may bedesirable to; include in a railway signaling systemfacih-tles'which Wlll permit an authorized work foreman to set a signal against proceeding into a section where work is going OIIWlllCh work will not permit traf- -fic;, This may be made possible by providing special signal arrangements, as that indi- .cated for the drawbridge, from point to point along the trackway, which signals can be thrown into operation by a key in possession of the foreman, as I have'shown in connec.-

tion with the special signal, where 29 is a key lock having a bolt 30 to'operate the switch 21, aswell as switch 27, through the connection between the two switches indicated by the broken line.

The foregoing provides for-exciting the track circuits of the various blocks with al.- ternating currents which set the wayside s-ig nals in accordance with phase of currents and/or absence ofcurrents depending upon track conditions, and for impressing upon 1 positions of the wayside signal relays, but is concerned with the code signals or interruptions in the current and the total absence of current.

, In Fig. 1 all of that part of the diagram above the track rails 1, 1 is illustrative of the apparatus carried by the locomotive. A pick-up coil 31 is attached to the locomotive preferably just forward of the forward truck 32 so as to be quite close to the track circuits. The pick-up coil circuit may be electrically tuned to the frequency of the signaling alternating currents in the track circuits, as by a condenser 33, to minimize possibility of interference from stray currents. I The received currentsare suitablyamplified by an amplifier 34, which may be of the well known three-electrode vacuum tube type in one or more stages, the circuits of the various stages being electrically tuned if desirable, to actuate the main receiver relay 35 controlling the switch 36. It should be noted that the switch 36 is held open when current flows in the track circuits, and closes during the interruptions that make the code signals and on a total failure of current. A rotativeelement 3?, having cam 37a, starts with spring contact 38 closed, and closes spring contacts 39, 40, 41 and 42 in succession. The element 37 is rotated by motor 43 through a friction wheel 44, rotatably fixed and slidably mounted on the shaft of the motor, capable of making friction driving contact with friction wheel 45 fixed to the rotative element. The rotative element is started and stopped by a pawl lever 46 cooperating with a notch in a rim 47 fixed to the element. A clutch arm 48 on the pawl lever 46 cooperates with the friction wheel 44 to bring about contact with the friction wheel 45 at the starting moment. With the ro-tative element at rest, as illustrated, contact 38 is closed, so that closure of switch 36 will send current from battery 50 through relay 49 to actuate pawl lever 46 to start the rotative element. Contact 38 immediately opens to deenergize the relay 49, leaving the pawl lever 46 riding on the surface of the rim 47 ready to stop the rotative element when one revolution is completed.

Referring temporarily to Fig. 4, which represents one of the signal producing wheels at the wayside stations, it will be seen that l have divided the circumference of the wheel into a one-third sector, having spaced insulating segments a, b, 0, (Z, and a two-thirds sector, having no segments, which sectors may be termed signaling and non-signaling respectively; Fig. 4a illustrates the current that will flow in a track circuit during one revolution of such a wheel, showing that the duration of current flow is long compared to the absence of current, which fact makes the design of a vv'ayside relay H that will not respond to the code signaling a simple matter.

The description so far will permit of fol lowing the Iirststep in the operation of the receiver on the locomotive. Referring to Figs. 4 and 1, the brush 1? comes to the insulating segment a on the signal producing wheel an interru Jt-ion in current takes place, causing the relay to release the switch 36 to close the main receiving circuit. The rotative element 3? is with contact 38 closed, which permits current to flow from battery 50 through contact 38 and switch 36 to energize relay 49, operating the pawl lever 46 to start the rotative element on a revolution. The brush 1? passes oil insulating segment at, permitting current to flow resulting in opening of switch 36. The movement of the'rota' tive element opens contact 38 to re main open until the end of the revolution, thus deenergizing relay 49 and leaving pawl lever 46 free to stop the rotative element. Brush 17 arrives at insulating segment 6, again closing switch 36. At the same time cam 37a of the rotative element closes contact 39, allowing current to flow from battery 50 in a circuit inclu ing switch 36 and contact 39. The same procedure results as brush 1'? passes insulating segments 0 and d and cam 3% passes contacts 40 and 41 respectively. l Vhen cam 37a, arrives at contact 38, brush 17 is on the non-signaling sector of the wheel and switch 36 is held open, so that contact 38 may be closed without energizing starting relay 49, but paves the way for repeating the cycle as soon as the brush again arrives at the signaling sector.

It is apparent that the relative angular velocities of the signaling wheel and the rotative element should be adjusted so that the rotative element completes one revolution in the same period of time, within limits, required for the signaling wheel to revolve through the signnaling sector, and that the relative spacing of the insulating segments on the signaling wheel and the contacts in the path of the rotative element cam should be such that corresponding units are reached at the same time, within limits; that is, synchronizedly rendered ready for action. ln practice, the signaling wheel and the rotative element cam are synchronized at every revolution of the former, the cam being held stationary by the lever 46 while the signaling wheel turns through that portion of its cycle during which the brush 1'? is in contact with the non-signaling sector, and the cam being started just as the signaling wheel turns its signaling sector a into contact with the brush 17. The duration of the signal interruptions at the signaling wheel or transmitter and the contact closures at the rotative element cam or receiver can be made sufficiently long to be certain of an overlap even with relative angular velocities difiering as much as 10% from exact synchronism. In practice there is no difiiculty in preserving motor speeds within 1 or 2% with ordinary commercial apparatus, and much better if precision warrants special apparatus. Since all of the transmission motors may be connected to the same alternating current trans mission line, as illustrated in Fig. 1, the same speed of all would be assured in the use of induction motors, which fact greatly simplifies the matter of adjustment of motor speed on the locomotive.

While l have divided the signaling wheel into one-third signaling and twothirds nonsignaling sectors, no such definite relation is required. It is desirable however to have a non-signaling sector of greater duration than the signaling sector because it may often 7 paratus and happen that conditions in the track may operate to cause the signaling wheel 16 to be moved out of contact with the brush 17 and the wheel 15 to be moved into contact therewith, which might cause the rotative cam 37 on the locomotive to start in response to an impulse derived from one of the intermediate insulating segments, such as b, c, or d on the wheel 15 and thus would operate the cam 3'? out of step, so to speak, with the wheel 15, giving a false signal. In the arrangement shown, the non-signaling sector on each signalingwheel permits the cam 37 to return to its original or initial position after each false start, so that the cam and the signaling wheel are never out cf step to give a false signal for nore than one revolution ofthe wheel. The false signal itself will not register, as will be later explained, and will do no harm as long as the rotative element comes to rest in timefor the correct starting sig-.

naling. The relatively wide non-signaling sector adequately provides for this.

Continuing with the description of the apoperation of the locomotive installation, the contacts 39 and 40 control circuits through relays 51 and 52 whichrelays' in turn determine the settings of multiple selector contacts 53 and 54 respectively. The multiple selector 53 is provided with three movable contacts 80, 81 and 55, and the selector 54 is provided with two movable contacts 82 and 56. The contacts, relays and multiple contacts may be termed the selector elements of the receiver; Now it is apparent that with two multiple contact elements, each capable of two positions, we can selectively choose any one of four circuits for closure; as I have illustrated, there are four combinations of positions which these multiple contacts may occupy, as follows: Both to the right; both to the left; upper one to right, lower one to left; and upper oneto left, lower one to right. Referring again to Fig. 4, the two positions occupied by the insulating segments 7) and 0 may be termed the selector positions, since they are the ones under the brush 17 when the selector contacts 39 and 40 are closed. The code signals are therefore made by inserting or leaving out insulating segments at these positions. 7

Now suppose when position b is reached there is no insulating segment, then in spite of the fact that contact 39 is closed switch 36 remains open due to continuation of current during this interval, and relay 51 is'not energized because contact 39 and switch 36 are in series with battery and relay 51. M ltiple contact I 3 therefore remains to the e'ht. ()n the other hand, if there is an in- SUl ng segment switch 36 closes, resulting in the multiple contact being pulled to the left. The same thing happens when selector position 0 is reached in regard to contact 40, relay 52 and multiple contact'54.

The multiple contacts 53 and .54 temporarily remain in the left hand positions, if so selected by the codesignals, after the openingof contacts 39 and 40 respectively, through the operation of stick circuits, closed through contact 55 for multiple contact 53 and through contact 56 for multiple contact 54. The stick circuit for therelay 51 may be traced as follows: From the battery 50 direct to the lower terminal of the relay5l,

from the upper terminal of the relay 51 to the contact element 55 whichis in its lefthand position, thence to the switch 57 and direct to the battery 50. The stick circuit for the relay 52 may be similarly traced as follows :From the battery 50 to the lower terminal of the relay 52, from the upper 36, thus energizing relay 58 to open switch 57, clearing out the stick circuits and returning the multiple contact elements 53 and 54 to normal position ready for a new signal. The energizingcircuit for the relay 58 includes the relay 49 which is therefore temporarily energized when the relay 58 is energized, but this energization of the, relay 49 has no effect on the operation of the apparatus as the cam portion 37a immediately disengages the contact 42 and de-energizes the relay 49, permitting the lever 46 to drop intothe depression in the collar 47 and thus stop the rotative element as describedabove. The signal circuits-will be traced hereinafter.

Before the clearing out operation takes place there is a signal of execution brought about by insulating segment don the wheel, which comes under the brush at the same time that contact 41, controlling relay 59, is closed. During the selection operations switch 60, operated by relay 59, remains open so that as each selector position is taken up there is no false selection of a control circuit. When the selector multiple contacts are finally set to choose the desired control circuit switch 60 is closed by a signal originating with segment 03 on the signaling wheel, and the selected control circuit thus energized by battery 50. Now this execution signal could be made locally as just previously described for the clear-out signal, but there is a decided advantage in having it originate with the transmitter. In case a false signal starts the rotative element would, in its passage through the various contacts, make some sort of false selection of multiple contact positions, and if the signal of execution isaccomplished locally, the false signal would be registered. But by requiring the signal of execution to originate at the transmitter after a definite true signal, there is little likelihood of a false signal ever being accompanied by a correctly timed signal of execution, and therefore registry of a false signal is not likely. This arrangement well provides for not registeringfalse signals due to shifting of signaling wheels, as previously described.

- However, even though a false signal should register, no harm would be done, as the true signals are rapidly repeated, two or three times a second being possible, so that any false signal would be corrected before it would have time to put any of the mechanical train control apparatus into operation, which is an extremely valuable feature of my system.

The system, as so far described, provides for selecting any one of a plurality of control circuits on the locomotive in accordance with any one of a plurality of code signal combinations, informative of track conditions, of a permanent, semi-permanent or temporary character, superimposed upon a track alternating current variable in characteristics in a manner suitable to operate wayside signal relays without interfering with the locomotive code signal combinations. The selectable control circuits may be made to control any desired functions on the locomotive, one at a time or in combination, such as lighting visual indicating colored lamps, operating warning bells or whistles,

controlling air brake mechanisms, setting cams, wh1ch determine the run down distance under application of brakes and speed limits imposed, and the like. The particular manner of putting the control circuits to workdoes not form a part of my invention.

" In Fig. 1, however, I have shown an illustrative use of the controlcircuits in connection with colored light visual indicators, it of course belng understood that an electr1c current which is available to light. a lamp may be made to do anything else desired, either directly or through well known intermediary apparatus. The four circuits, as and when selected, energize relays 61, 62, 63 and 64: through battery 50. lVhen the relay selected is energized to close one of the contacts 65, 66, 67 and 68 respectively, current flows from the battery 69 through one of the lamps B, Y, G and G respectively as well as the winding of the corresponding relay to keep the light circuit permanently closed, as the energizing by the battery is only temporary during the signal of execution. For instance, I have shown the second G lamp lighted through closure of contact 66.

' To keep this lamp from remaining lighted in case a signal for another one is made I provide the conducting wheel 70 ci uit with the battery 69 and the lamps through brush 72, the wheel. having an insulating segment 71. The wheel rotates in synchronism with the rotative element 47, indicated by the broken line connection between the two as by belng on the same shaft, and the insulating segment is so located as to come V of clear if track grades, curves and the like warrant imposing diiferent speeds under clear track conditions.

In order to illustrate the manner in which the various locomotive or cab signals shown may be displayed by difierent code signals from the various wayside signal wheels, I will now trace the locomotive signal pick-up circuits. If one of the signaling wheels, say the wheel 16, is connected to the track rails of the block in which the vehicle under consideration is travelling, and this wheel is provided with the insulating sectors a, 0 and at only, the sector 6 being a conducting portion, the relay 51 remains de-energized while the relay 52 is energized at the rotation of the element 37. The multiple contact selector 53 therefore remains in the right-hand position while the selector 54 is moved to the left-hand position, and when the relay 59 is energized by r the signal of execution, closing the switch 60, the following pick-up circuit for the relay 61 is completed :From the battery 50, through the switch 60 to the contact 82, thence through the left-hand stationary contact to the movable contact 81, and to the lower terminal of the relay 61, from the upper terminal of the relay 61 to the battery 50. The energization of the relay 61 closes its front contact, thus completing a stick circuit for this relay through the left-hand signal lamp G, this circuit being traceable as follows :From the battery 69 to the upper terminal of the relay 61, from the lower terminal of 61 through its front contact and contact finger, through the lamp G, the brush 7 2 and the wheel 70 to the battery 69.

In a similar manner, if both of the insulating sectors 6 and 0 are omitted from a wayside signaling wheel which may be the signaling wheel 15, both of the multiple contact selectors 53 and 5e remain in their right-hand positions as shown, and upon the signal of execution closing the switch 60, a pick-up circuit for the relay 62 is completed, which circuit may be traced as follows :From the battery 50, switch 60, movable contact 82 of the selector 54, movable contact of the selector 53, relay 62 and back to the battery 50, the energization of the relay 62 closing a stick circuit through its front contact 66 and the signal lamp Y indicating the battery 69, the

wheel 7O and the brush 72, which circuit is obvious from thedrawings g With the insulating sector 0 omitted from the wayside signaling wheel, which may .be the. special wheel 28, the selector 53 is placed in the left-hand position while the selector 54 remains to the right, and when the switch 60 is closed by the signal of execution, a picL- up circuit for the relay 63 closed from the battery 50 through the switch-60, the movable contact 83 of selector 54 and the movable contact 80 of selector 53, the relay 63 and re turn to the battery 50. The energization of the relay 63 closes its front Contact 67 and 1 completes stick circuit for this relay from the battery 69, this circuit including the special signal lamp G and being traceable in a similar manner to the stick circuits for the lamp Y and the left-handlanip G.

If a special wayside signal wheel 28 has bothof the'insulating sectors?) and c, or for any reason no signaling current flows in the trackcoils or is received by the locomotive coil 31, both of the relays 51 and 52 are energized in the rotation of the element 3? and both of the selectors 53 and 54 are moved to the left, completing a pick-up circuit, when the switch 60 is closed by the signal of 8X6CL1- tion, which pick-up circuit energizes the relay 64. This circuit may be traced as folsponse to different codes or successions of:

time-spaced interruptions in the trackway current-may be utilizedto communicate certain trackway or traffic conditions to the. en.- gineer. may indicate clear no speed limitations,

the signal lam Y may indicate caution that usually precedes danger signal, other signal lamp G clear with track structuralconditions in block which require caution, and the right-hand signallamp R- stop and Any other suitable combination of.

stay. signals or other indicators maybe used in place of the specific'arrangement shown, or

Lthe stick circuits of the relays 61, 62, 63

and 64 may be utilized to operate suitable brake control apparatus to control the train speed'in accordance with the trafic or track-' way conditions encountered.

An important feature ofrmy invention is that it meets, in-a very simple way, the broad fundamental requirement that a failure of current will register as a danger signal both at the wayside stations and on the com0-- tive. I have already shown howabsence'of Thus the left-hand signal lamp current in the trackcircuit iblocks,xthrough any cause whateven will set the wayside vis ual signals at danger indication through the operation ofthe polyphase motor relays H. It will be notedthat instead of the usual procedure of operating. areceiving relay dur ing current flow I'employ a no current period or interruption. "Therefore when there is no current in the block entered by the locomotive the relay is. continuously deenergized,

leavingthe switch 36 always closed, with the result that the rotative element continues to rotate, each timeset-ting all the relays just as if a. signalwheel having-all the selector positions insulated as illustrated in Fig. 4 were rotating, and making a signal of execution and clear-out signal. By adopting the control circuit selected by having all of multiple contact selectors to the left as the danger control circuit, danger is indicated on thelocomotive by current failure. Should current fail in'the transmission line '7 or in the feeders to the transformer T, the track circuits of the blocks fed will be without current and indicate the fact at the-wayside sigable practical circuits. In referring to Fig.

4, I stated that positions 6 and c on the wheel are the selector posit-ions. Now if we increase the number of such positions to three a a I V V 7 increasing the corresponding selector ele ments at the receiver, eight combinations will be possible. Four selector positions and corresponding receiver selector elements makes sixteen selections possible, and live setsof: positions and elements makes thirtytwo selections possible. Extremely simple and practical apparatuscapable of thirty two selections is a proven success.

VVhile I have illustrated the selector as an arrangement of electrical contacts. and relays, I have done this merely for the sake of simplicity of explanation of the system. The same result can be accomplished through system of mechanical selectors cooperating. with the relay 35 and the rotative element 47. I do not, however, make any claim to the selector system per se;

Thesystemis particularly adapted to railways having only portions of their systems equipped for signaling. Under such conditions it is desirable to inform the locomotive when it leaves signaled territory and to set the locomotive apparatus against 'makingnot having signaling currents, as well as to inform the locomotive when it is about to enter signaled territory and to set the appa ratus for receiving signaled territory signals.

Tn Fig. 2 T illustrate a portion of the trackway of the last block of signaled territory and a portion of the trackway of the nonsignaled territory comprising rails 1, 1 and insulated joints 2, 2. The signaled block is excited with current from a transformer T as previously described. A short section of the non-signaled territory just beyond the last block is excited with a signaling current through a transformer NT, a special signaling wheel 28 on the shaft of the motor 18 superimposing upon the current a code combination meaning leaving signaled territory. The special signaling wheel 28 is connected to the transformer N T through a circuit including the generator 7, the lower wire of the transmission line '5', through a resistance unit 20 and a brush to the shaft of the rotor 18, from the wheel 28 through the brush bearing thereon to the primary of the transformer HT, and thence through the upper wire of the transmission line 7 to the generator 7. The special track circuit is completed through an ordinary two-position relay H, as there are only two track conditions to indicate, one being when the special track circuit is not occupied, indicating a clear condition, and the other when the track circuit is occupied, indicating a danger condition, as illustrated in Fig. 2 by the truck 32 of a locomotive in the section. The relay H makes contact at 9 or 10 accordingly as the special section is or is not occupied to show lights G or R and also to excite relays 12 or 11, operating lever 13 to set wheels 15 or 16 and pole changing switch 19 as previously described.

The special signal is collected on the locomotive and selected as in the case of Fig. l, and I have not again illustrated the selector system in detail. It should be understood that the pick-up circuits for the relay connected to the selector in Fig. 2, including the relay 7 3, are selectively closed in response to distinctive code sig nals from various wayside signaling wheels, and that the particular code signal impressed on the track rails of the first short section of non-signaled territory through the transformer N T operates the selector to close a pickup circuitfor the relay 73. The en ergization of the relay 73 closes its front contact and completes a stick circuit including the signal lamp NS, one winding of the relay 74:, wh ch circuit may be traced as follows From the battery 69, upper terminal of the relay 73, lower terminal of this relay through its front contact and contact finger, lamp NS, one winding of the relay 7%, brush and wheel to the battery 69. The relay 74: is preferably constructed with two separate windings, these windings being arranged so that longer proceeding under the protection of automatic control. The energization of the relay 74 through the stick circuit traced closes the switch 76 and opens the switch 75. The closure of the switch 76 shunts out the wheel 70 and its brush through an obvious circuit thus preventing the insulating se ment in the wheel 'ZOfrom opening the stick circuit to the relay 73. The opening of the switch 7 5 pre vents the energization of the danger signal lamp R as the train proceeds in non-signaled territory. As the train proceeds out of the lock energized by the transformer NT, no code signal is transmitted to the selector, and hence the selector circuits act to close a pickup circuit for the relay associated with the lamp R as described in connection with Fig. 1. This relay is therefore energized, but the lamp is not lighted as no stick circuit for this relay is completed due to the fact that the switch '7 5 in this stick circuit is opened as explained above, and is maintained opened as the train proceeds through the nonsignaled territory by the relay 74.

Fig. 3 illustrates an arrangement for. informing the locomotive of arrival at signaled territory and setting the apparatusfor normal signaling reception. The track rails 1, 1 are divided into track circuits by insulated joints 2, 2, the section from A to A being the first block containing locomotive signaling current, and the point A being the first point having wayside signals. The section AA is excited with signaling currents in a manner fully described heretofore. Immediately in advance of the point A the rails have impressed upon them signaling current through the transformer ST, and a special signal superimposed on the current by the signal producing wheel 28 on the shaft of the motor 18. Special insulated joints 2 may be inserted in the rails to limit the distance to which the special signaling current will he efiective. No current will flow until the truck 32 of the locomotive passes beyond the joints 2 to complete the circuit.

The code signal supplied to the track rails of the last short block in non-signaled territory through the transformer ST from the wheel 28 is arranged to cause the selector on the locomotive to close a pick-up circuit for the relay 77 in a manner similar tothe energization of the relays 61, 62, 63 and 64: described in connection with Fig. 1. The energization of the relay 77 closes its front con- 1 the protection of automatic control.

tact and completes a stick circuit through the lamp S, which circuit will be traced as folloWs:From the battery 69, through the relay 77, and the front contact and contact finger thereof, the signal lamp S, the opposalready flowing through the normal attract ing winding of this relay and the stick circuit including the relay 73 and the lamp NS which circuit has been traced above, relay 7 4 no longer holds the switch 7 5 openand the switch 75 is moved by the spring to its closedor left-hand position, thus opening switch 76 connected thereto. The energization of the light S informs the engineer that he has entered signaled territory and is again under The closureof the switch 7 5 completes the stick circuit for the danger lamp B so that this, lamp may be energized in response to danger code signals which may be transmitted from :the trackway as the train proceeds in signaled territory. The opening of the switch 76 removes the shunt from the wheel and its brush, thus permitting this wheel to pcriodically break the stick circuits for all the signal relays as described in connection with Fig. 1. While the train is in the block energized by the transformer ST, relay 77 will be repeatedly energized and the lamp S lighted; Current will flow-through the winding of the relay 74 in series with the lamp S after the circuit through the other winding of the relay 74 has been broken but this current does not cause an attraction of the armature 75. Fig. 3 illustrates thiscondition of the circuits, in Whichthe circuit through the lamp S is closed and that through the lamp NS is broken, switches 75 and 76 remaining in their left-hand positions. The signal S i's'displayed only while the train isin the track block energized by the transformer ST, and when the train enters the first block A-A of a signaled territory the proper locomotive signal lamp is lighted in accordance with traffic conditions ahead 1n the manner described in connection, g a plurality of electrically d ti c e with Fig. 1. 7

Having fully described my inventi0n,"I claim:

-1. In a system of sectional electrical signaling, a method'of signaling which consists of dividing the system into a plurality of electrically distinct sections, exciting each section with alternating current signaling current, superimposing code signal variations on said signalmg current to make one group of signals, and varying the phase characteristics'of said current without regard to said code signals to make another group of signals. 2.

Inasystem of electrical signaling the:

method of multiple signaling which consists of generating a single alternating current signaling current, varying the phase of said alternating current to create one groupv of signals, and superimposingtimespaced var ations upon sald current Without regard .to said phase variations to create another group of signals.

. 3. A method of electrical signaling which consists of continuouslygenerating an alternating current signaling current, superimposing code signals on said alternating cui'i rent to make one group of signals, and varying the phase characteristics of said currents without regard to said code signals to make another group of signals. p v

4-. A method of electrical signaling which consists of continuously generating an alternating current signaling current, dividing a definite time period of said current intotwo portions, superimposing code signals on one of said portions to make one group of signals, andvarying the phase characteristics of said currents to make another group of signals. 7 I

5 A system of electrical signaling including means for the continuous generation of alternating current signaling current, means for superimposing on said current timespaced variations characteristic of predetermined code signals, and means for varying the phase characteristics of said alternating current without regard to said signal varia; tions. i V

6. A system of electrical signaling includ; ing means for the continuous generation of alternating current signaling current, means for impressing code signal variations on said current, and means for varying the phase characteristics of said current without regard to said code signals. 7 I

'7. A system of electrical signaling including a plurality of electrically distinct sections, means for exciting each section with alternating current signaling current, means.

for superimposing code signal variations on said current, and means for varying the phase characteristics of said current without regard to said code signal variations.

8. A system of electrical signaling including a plurality of electrically distinct sec tions, a circuit for exciting each section with alternating current, means for changing the phasecharacteristics of said current, means for detectlng said phase changes, a plurality of means: for superimposing code s1gnalya=riations: on saidcurrent, and means whereby said phase change detecting means determines the phase and code signal impressed upon an adjacent section.

' 10. A system of electrical signaling including a series of electrically distinct circuits, means for exciting each of said circuits with alternating current signal current, means for impressing any one of a plurality of code signals on said current, means for changing the phase of said current, and means interlinking said circuits whereby the phase of said current determines the phase and code signals impressed upon adjacent circuits.

11. A system of electrical signaling including a series of electrically distinct circuits, means for exciting each of said circuits with alternating current signal current, means for superimposing code signal variations on said current, means for changing the phase of said current, a receiver in each of said circuits responsive to phase changes and unresponsive to said code signal variations, and a receiver which may be associated with any one of said circuits responsive to said code signals and unresponsive to said phase changes.

12. A system of electrical signaling including 'a series or" electrically distinct circuits, means in said system consuming electrical energy including means for exciting said circuits with alternating signaling current, a rotative means for superimposing code signal variations on said current, means for changing the phase of said current, means for detecting the phase of said current, visual indicating means, means for varying the code signals, and a common source of supply for all of said energy consuming means.

' 13. -A system of electrical signaling including a series of electrically distinct circuits, means for energizing each of said circuits with alternating current and imposing distinctive signals controlled by signals in adjacent circuits on said alternating current, and independent means in one or more of said circuits for suppressing the normal signal in at least portions of said circuits and impressing thereon a special code signal.

14. A system of electrical signaling including a series of electrically distinct circuits,

means for energizing each of said circuits with alternating current and imposing distlnctlve signals controlled by signals in ad- Jacent circuits on said alternating current,

7 independent means in one or more of said circuits for suppressing the normal signal in at least portions of said circuits and impressing thereon a special cod-e signal, and means controlling the going in or out of operation of said independent means.

15. A system of electrical signaling including a series of electrically distinct circuits, means for energizing each of said circuits with distinctivesignal impulses controlled by signals in adjacent circuits, independent means in one or more of said circuits for suppressing the normal signal impulses in at least protions of said circuits and impressing thereon special signal impulses, and a look ing meansfor the placing of said independent means in or out of operation.

16. A system of electrical railway signaling including a track circuit, means for continuously exciting said circuit with alternating current signaling current, means for superimposing code signal variations on said current, means for changing the phase of said current, a receiver in said circuit responsive to phase changes and unresponsive to said code signals, and a receiver associated with said circuit responsive to said code signals and unresponsive to said phase changes.

17. A system of electrical railway signaling including a track circuit, means for continuously exciting said circuit with alternating current signaling current, a code transmitter superimposing signals on saidcurrent, means for changing the phase of said current, a receiver in said circuit responsive to said phase changes and unresponsiveto said code signals, and a code receiver associated with said circuit.

18. A system of electrical railway signaling including a track circuit, means for continuously exciting said circuit with alternating current signaling current, means for superimposing code signal variations on said current, means for changing the phase of said current, a receiver in said circuit responsive to said phase changes and a failure of current and unresponsive to said code signals, and a receiver associated with said circuit responsive to said code signals and a failure of current and unresponsive to said phase changes.

19. A system of electrical railway signaling including a plurality of electrically dis tinct blocks, means for continuously exciting each of said blocks with an alternating signaling current, means for superimposing code signals on said current, and means for varying the phase of said current.

20. A system of electrical railway signaling including a plurality of electrically distinct blocks, -means for continuously exciting each of said blocks with an alternating signaling current, means for superimposing a plurality of code signal variations on said current, means for varying the phase of said current, means in each of said blocks for detecting phase variations, and means linking adjacent blocks whereby the phase variations in one block control the'phase adjustment and code signal variations in an adjacent block.

21. A system of electrical railway signaling including a plurality of electrically distinct blocks, means for continuously exciting each of said blocks with an alternating signaling current, means for superimposing code signal variatlons on said current, means for varying the phase of said currents, a rebe associated with any one of said blocks responsive to code signal variations and unresponsive to phase variations. 7

22. A system of electrical railway signaling including a plurality of electrically distinct blocks, means for continuously exciting each of said blocks with an'alternating signaling current, means for superimposing code signal variations on said current, means for varying the phase of said current, a receiver in each of said blocks responsive tophase variations and failure of current and unresponsive to code signal variations, and a receiver which may be associated with any one of said blocks responsive to code signal variations and failure of current and unresponsive to phase variations.

23. A system of electrical railway 'signaling including a track circuit, means for exciting said circuit with alternating signal current, means for varying the phase of said signal current, wayside visual signals, means in said track circuit responsive to said phase variations and failure of'current selecting the setting of said Wayside signals, means for superimposing a plurality of code signal variations on said track current, and means operating in accordance with the setting of said Wayside signals for selecting said code signals. I

24. A system of electrical railway signaling including a series of electrically distinct blocks, means for energizing each of said blocks with distinctive signal impulses controlled by signals in adjacent blocks, independent means in one or more of said blocks for suppressing the normal'signal impulses in at least portions of said blocks and impressing thereon special signal impulses, and a locking means for the placing ofsaid independent means in or out of operation.

25. A system of electrical railway signaling including a series of electrically distinct blocks, means for energizing each ofsaid blocks with distinctive signal impulses controlled by signals in adjacent blocks, all comprising signaled territory; an unsignaled track at the exit end of said signaled territory, a section of track circuit between said unsignaled track and the exit end of said signaled territory, and means for exciting said section'with a distinctive code signal.

26. A system of electrical railway signaling including a series of electrically distinct blocks, means for energizing each of said blocks with distinctive signal impulses 'controlled by signals in adjacent blocks, all comprising signal territory; an unsignaled track at the entrance endof said signaled territory, a section of track circuit between'said unsignaled trackand the entrance end of said signaled territory, and means for exciting said section with distinctive code signal impulses.

27. A system of electrical railway signaling including a track circuit, means for continuously exciting said circuit with signaling current, means for dividing said signaling current, means for dividing said signalportions, means for superimposing code signals on one of said portions, a railway-vehicle, and a code receiver on said vehicle re sponsive during said signaled portion of the time periods.

283Asystem of electrical railway signal-- ing including a track circuit, a rotary transmitting device for impressing a plurality of time-spaced code signals on said circuit, a

vehicle passing over said track, a plurality of control elements on said vehicle, and a rotary receiver periodicallysynchronized with said rotary transmitting device and adapted toselectively energize said control elements in accordance with any one of said signals.

, 29. A system of electrical. rail way' signaling including a track circuit, means for pressing a plurality of code signals on said circuit, a vehicle passing over said track, a plurality of control elements on said vehicle, a code receiver associated with and momentarily selectively energizing said control elements in accordance with said signals, and

means for locking said elements in operating position when so selected.

30. A system of electrical railway signaling including a track circuit, means for impressing a plurality of code signals onsaid circuit, a vehicle passing over said track, a plurality of control elements on said vehicle, a code receiver associated with and momentarily selectively energizing said control elements in accordance with said signals,means locking said elements in operating position when so selected, and means releasing a locked element when another element is se ing includinga track circuit, means forcon-- tinuously exciting sections of said track circuitwith alternating current signaling cur-- rent, means for impressing codesignal variations on said current, transient means interrupting the flow of current in portions of said sections, a railway vehicle passing over said track, a codev receiver'on said vehicle, a magnet to operate said receiver adapted to actuate the same on a cessation of current, and a control circuit on said vehicle adapted to: be continuously selected and energized by said code receiver when continuously actu-- ated. through a prolonged cessation of current.

32. A system of electrical railway signal ing" including a railway vehicle, a plurality of-control elements on saidvehi'cle", a code reire ceiver associated with and selectively energizing said elements and means for interlocking three o1 said control elements whereby the energizing of one of saidinterloc'ked elements will render the other inoperative until the energizing of the third elementreleases said interlocking.

33. In an automatic train control system, means for communicating influences corresponding to trathc conditions from the trackway to a moving vehicle comprising a continuously driven trackway device for recurrently impressing a pre-arranged series of time-spaced electrical impulses on the track rails, car-carried means for inductively receiving said impulses through an intervening air gap, and car-carr ed apparatus for responding to said impulses, said car-carried apparatus being continuously driven in synchronism with said trackway device while said impulses are being transmitted.

34. In an automatic train control system, means for communicating influences corresponding to traflic conditions from the track- Way to a moving vehicle comprising trackway apparatus comprising means for apply-' ing an alternating current to the track rails through one of a plurality of continuously driven commutators, each of said commutators acting to interrupt said current at different pre-arranged series of time-spaced intervals, means for reversing the phase of said alternating current in accordance with traffic conditions, means for controlling the interruption of said current by different commutators in accordance with the phase of said alternating current, and car-carried means for inductively receiving said current and responding to said series of interruptions.

35. In an automatic train control system for railways having portions of their trackway equipped for automatic train control and portions not so equipped, means for communicating influences corresponding to trackway conditions ahead from the trackway to a moving vehicle comprising trackway apparatus for applying electrical energy to trackway conductors in said equipped portions and recurrently interrupting said energy at a pre-arranged succession of intervals in accordance with tralfic conditions ahead, for the trackway apparatus at the entrance to and the exit from said unequipped.

way with code impulse combinations, means for varying the number of impulses in a combination in accordance with traffic conditions,

a plurality of contacts on the train, means for selectlvely operatmg said contacts in accordance wlth the number of lmpulses in a combination being supplied to the trackway,

said contacts, and governing means con-.

trolled by said relays.

38. In an automatic train control system of the continuous inductive coded type; the combination with trackway apparatus for impressing code cycles on the track rails in which the code cycles may have different numbers of impulses in a cycle or have the same number of impulses difierently time spaced, and car-carried apparatus distinctively responsive to said code cycles.

39. In an automatic train control system of the continuous inductive coded type; the combination with trackway apparatus for impressing code cycles on the track rails in which the code cycles may have dilferent numbers of impulses in a cycle, the same number of impulses in a cycle diflere'ntly spaced or cycles in which both the number of impulses and their spacing is different than that of other cycles; and car-carried apparatus distinctively responsive to said code impulse cycles.

. 40. In an automatic train control system of the continuous inductive coded type; the combination with trackway apparatus for impressing code cycles on the track rails in which the code cycles may have ditferent numbers of impulses in a cycle and differently time spaced than the impulses of other code cycles, and car-carried apparatus distinctively responsive to said code impulse cycles.

41. In an automatic train control system of the continuous inductive coded type; the combination with trackway apparatus for impressing code cycles on the track rails in which the code cycles may have different numbers of impulses in a cycle and car-carried apparatus responsive to said code cyc-les requiring an initiating impulse to be transmitted from the trackway to render it effective and requiring the transmission of an executing impulse from the trackway to cause it to interpret the code cycle transmitted between this initiating and executing impulse.

EDWARD n. LoFTIN; 

